vendredi 19 septembre 2008

Sagitta

Sagitta is the third-smallest of all constellations (only Equuleus and Crux are smaller). Ptolemy included it in his list of 48 constellations. At that time, however, it was even smaller, spanning only about 4 sq. deg. It is also on the list of 88 constellations now acknowledged by the IAU.Located not very far to the north of the equator, this constellation can be seen from everywhere on Earth except for within the Antarctic circle.Sagitta is surrounded by the following constellations (beginning at the north and then continuing clockwise): the little fox Vulpecula, the mythological hero Hercules, the Eagle Aquila and the Dolphin Delphinus. It lies in the Milky Way, pointing eastward and shows clearly the shape of an arrow flying towards the Swan, Cygnus. Although ancient, is insignificant, for it has no star larger than the 4th magnitude. The Five Stars are its most noticeable feature. Sagitta was its common title with all the Romans who mentioned its stars.It has been regarded as the traditional weapon which Hercules used to kill the eagle (Aquila) of Jove that perpetually gnawed Prometheus' liver. The Arrow is located slightly above the Eagle. Some see the Arrow pointing to the east, others to the west. In conjunction with the story of Aquila it should be seen pointing to the west, aimed at the Eagle. Others believe the arrow to be the one shot by Hercules towards the adjacent Stymphalian birds (6th labor) who had claws, beaks and wings of iron, and who lived on human flesh in the marshes of Arcadia - Aquila the Eagle and Cygnus the Swan, and Lyra the Vulture - and still lying between them, whence the title Herculea. Eratosthenes claimed it as the arrow with which Apollo exterminated the Cyclopes. It sometimes was the Arrow of Cupid's bow.